Substituted 2-(phosphinyloxymethyl)-1,2,5-thiadiazolidin-3-one 1,1-dioxides and compositions and method of use thereof

ABSTRACT

Substituted 2-(phosphinyloxymethyl)-1,2,5-thiadiazolidin-3-one 1,1-dioxides, pharmaceutical compositions containing them and methods for the treatment of degenerative diseases utilizing them.

BACKGROUND OF THE INVENTION

(a) Field of The Invention

The invention relates to substituted2-(phosphinyloxymethyl)-1,2,5-thiadiazolidin-3-one 1,1-dioxides, topharmaceutical compositions containing the same and to the method of usethereof in the treatment of degenerative diseases.

(b) Information Disclosure Statement

The inhibition of proteolytic enzymes by nontoxic reagents is useful inthe treatment of degenerative disorders, such as emphysema, rheumatoidarthritis and pancreatitis, in which proteolysis is a substantiveelement.

Protease inhibitors are widely utilized in biomedical research. Serineproteases are the most widely distributed class of proteolytic enzymes.Some serine proteases are characterized as chymotrypsin-like orelastase-like based upon their substrate specificity.

Chymotrypsin and chymotrypsin-like enzymes normally cleave peptide bondsin proteins at a site at which the amino acid residue on the carboxylside is typically Trp, Tyr, Phe, Met, Leu or another amino acid residuewhich contains aromatic or large alkyl side chains.

Elastase and elastase-like enzymes normally cleave peptide bonds at asite at which the amino acid residue on the carboxyl side of the bond istypically Ala, Val, Ser, Leu or other similar, smaller amino acids.

Both chymotrypsin-like and elastase-like enzymes are found inleukocytes, mast cells and pancreatic juice in higher organisms, and aresecreted by many types of bacteria, yeast and parasites.

Cha, Biochem. Pharmacol., 1975, 24, 2177-2185, discusses kineticapproaches to the study of the binding of inhibitors to macromolecules,such as enzymes, and methods for the determination of such parameters asthe inhibition constants, reaction rates and bound and unbound enzymeconcentrations.

Groutas et al., Biochemical and Biophysical Research Communications1994, 198(1), 341-349 disclose compounds of the formula: ##STR1##wherein R₁ is H, methyl, benzyl, CH₂ COOt-Bu or CH₂ COOBz1 and their invitro inhibitory activity towards human leukocyte elastase.

Muller and DuBois, J. Org. Chem. 1989, 54, 4471-4473 disclose compoundsof the formula: ##STR2## wherein R is H, CH₃, benzyl or (CH₂)₂ SCH₃. Thecompounds were tested for sweet taste activity and were found to be notsweet or to have sweetness potencies of less than 10 times sucrose.

Lee et al., J. Org. Chem. 1989, 54, 3077-3083 disclose the synthesis ofcompounds of the formula: ##STR3## wherein R is phenethyl, phenyl or1-naphthyl. No utility is disclosed for these compounds.

Lee and Kohn, Journal of Pharmaceutical Sciences 1990, 79(8), 716-718disclose compounds of the formula: ##STR4## wherein R⁴ is phenethyl,phenyl or 1-naphthyl and R^(4') is hydrogen, or R⁴ and R^(4') are bothphenyl. The compounds were tested for anticonvulsant activity and threeof the four compounds were found to be devoid of anticonvulsantactivity.

Hanewacker et al., Arch. Pharm. 1993, 326, 497-498 disclose thesynthesis of compounds of the formula: ##STR5## wherein R is CH₂CH(CH₃)₂, cyclopropylmethyl, CH₂ Ph, (CH₂)₂ Ph, 2-furanylmethyl,1-naphthylmethyl, or 3-indolylethyl.

Unterhalt and Hanewacker, Arch. Pharm. 1988, 321, 375-376 disclose thesynthesis of compounds of the formula: ##STR6## wherein R is hydrogen,methyl, isopropyl, CH₂ CH(CH₃)₂ or benzyl without an indication ofutility.

Unterhalt and Hanewacker, Arch. Pharm. 1988, 321, 749-751 disclose thesynthesis of compounds of the formula: ##STR7## wherein R═CH₃, R¹ ═H andR² ═3-indolylmethyl; R═CH₃, R¹ ═H, and R² ═phenyl; R═C₂ H₅, R¹ ═H, andR² ═phenyl; R═isopropyl, R¹ ═H, and R² ═phenyl; R═methyl, R¹ ═CH₃O(O)CCH₂, and R² ═H; R═CH₃, R¹ ═HO(O)CCH₂ and R² ═H; R═CH₃, R¹ ═C₂ H₅and R² ═phenyl; R═R¹ ═R² ═CH₃ ; and R═C₂ H₅, R¹ ═R² ═CH₃.

Aouf et al., Tetrahedron Letters 1991, 32 (45), 6545-6546 disclose thesynthesis of 4-phenylmethyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide.

Dewynter et al., Tetrahedron 1993, 49(1), 65-76 disclose the synthesisof compounds of the formula: ##STR8## wherein R is CH₂ Ph or CH₂ CH(CH₃)(C₂ H₅).

Dunlap et al., U.S. Pat. No. 5,236,917, issued Aug. 17, 1993 disclose aseries of 2-substituted saccharin derivatives, such as4-(1-methylethyl)-2-[(3-oxo-1,2,5-thiadiazolidin-2-yl)methyl]-1,2-benzisothiazol-3(2H)-oneS,S,1,1-tetraoxide, 2-(1-methyl-1H-tetrazol-5-yl-thiomethyl)saccharinand various 2-halomethyl saccharin derivatives, which are stated to beuseful in the treatment of degenerative diseases.

Strasser et al., German Patent Application DE 4141218, published Jun.17, 1993, disclose a series of thiadiazolidin-3-one 1,1-dioxidederivatives as intermediates in the synthesis of various1,1-dioxo-[1,2,6]thiadiazinecarboxamides which are stated to bepotentially useful as analgesics, antipyretics and inflammationinhibitors.

Desai et al., U.S. Pat. No. 5,187,173, issued Feb. 16, 1993, disclose aseries of 2-saccharinylmethyl, 4,5,6,7-tetrahydro-2-saccharinylmethyland 4,7-alkylene bridged-4,5,6,7-tetrahydro-2-saccharinylmethylphosphates, phosphonates and phosphinates which are stated to be usefulin the treatment of degenerative diseases. A similar disclosure is foundin U.S. Pat. No. 5,296,496, issued Mar. 22, 1994.

SUMMARY OF THE INVENTION

The invention relates to compounds of the Formula I: ##STR9## wherein R¹is hydrogen, lower-alkyl, or phenyl-lower-alkyl; R² is hydrogen,lower-alkyl, or phenyl-lower-alkyl; R³ is hydrogen, or lower-alkyl; orR² and R³ together are --(CH₂)_(n) -- wherein n is 3 or 4; and A and Bare independently hydrogen, lower-alkyl, phenyl, or phenyl-lower-alkyl;or a pharmaceutically acceptable acid-addition salt thereof; or whereapplicable, an enantiomer or a racemic mixture thereof.

The compounds of the present invention inhibit the activity of serineproteases, specifically human leukocyte elastase, and are thus useful inthe treatment of degenerative disease conditions such as emphysema,rheumatoid arthritis, pancreatitis, cystic fibrosis, chronic bronchitis,adult respiratory distress syndrome, inflammatory bowel disease,psoriasis, bullous pemphigoid, periodontal disease, andalpha-1-antitrypsin deficiency.

Preferred compounds of the Formula I above are those wherein R¹ ishydrogen, or lower-alkyl; R² is hydrogen, or lower-alkyl; R³ is hydrogenor lower-alkyl; or R² and R³ together are --(CH₂)_(n) --; and A and Bare independently hydrogen, lower-alkyl, or phenyl-lower-alkyl.

Particularly preferred compounds of the Formula I above are thosewherein R¹ is hydrogen, or lower-alkyl; R² is hydrogen, or lower-alkyl;R³ is hydrogen, or lower-alkyl; or R² and R³ together are --(CH₂)_(n)--; and A and B are independently lower-alkyl, or phenyl-lower-alkyl.

Preferred species of the Formula I above are2-(diethoxyphosphinyloxymethyl)-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide and2-(dibenzyloxyphosphinyloxymethyl)-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide.

The invention further relates to a pharmaceutical composition for thetreatment of degenerative diseases which comprises a pharmaceuticallyacceptable carrier, adjuvant, diluent or vehicle together with aneffective proteolytic enzyme inhibiting amount of a compound of theFormula I.

The invention further relates to a method for the treatment ofdegenerative diseases which comprises administering to a patient in needof such treatment an effective proteolytic enzyme inhibiting amount of acompound of the Formula I.

DETAILED DESCRIPTION INCLUSIVE OF PREFERRED EMBODIMENTS

The term lower-alkyl as used herein means linear or branched hydrocarbonchains having one to about five carbon atoms and thus includes methyl,ethyl, propyl, isopropyl, n-butyl, sec-butyl, 3-methylbutyl; n-pentyl,and the like.

The term halogen or halide as used herein means chlorine, bromine,iodine, and fluorine.

The numbering system used throughout this specification is shown in thering system which is illustrated below. This ring ##STR10## system isnamed in the chemical literature as a 1,2,5-thiadiazolidin-3-one1,1-dioxide.

The synthesis of the compounds of the invention may be outlined as shownin Scheme A: ##STR11## A suitably substituted2-halomethyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide derivative of theformula II, wherein X is a halogen, preferably chlorine, in a suitableorganic solvent, i.e. methylene chloride, is treated with an excess ofan acid of the formula III, in the presence of an excess of a base, i.e.triethylamine, optionally in the presence of a catalytic amount of atetraalkylammonium halide, preferably tetrabutylammonium bromide, at atemperature in the range of about room temperature up to the boilingpoint of the solvent used, preferably at the boiling point of thesolvent used, to afford the compounds of the formula I.

Alternatively, the compounds of the formula I can be prepared byreacting a suitably substituted 2-halomethyl-1,2,5-thiadiazolidin-3-one1,1-dioxide derivative of the formula II with an alkali metal salt of acompound of the formula III, preferably the cesium salt (prepared by thereaction of a compound of formula III with an alkali metal carbonate,such as cesium carbonate), in a suitable organic solvent, such asdimethylformamide, at a temperature of about room temperature.

Simple chemical transformations which are conventional and well known tothose skilled in the art of chemistry can be used for effecting changesin the functional groups of the compounds of the formula I. For example,catalytic debenzylation of benzyloxyphosphinyl groups to afford thecorresponding hydroxyphosphinyl group.

It will be appreciated that the compounds of the formula I possess anasymmetric carbon at position C-4 of the 1,2,5-thiadiazolidin-3-one1,1-dioxide ring and are thus capable of existing as enantiomers. Unlessotherwise specified herein, the invention is intended to extend to eachof the enantiomeric forms including the racemates. In some cases theremay be advantages, i.e. greater potency, to using a particularenantiomer when compared to the other enantiomer or the racemate in thetreatment of degenerative diseases and such advantages can be readilydetermined by those skilled in the art. The separate enantiomers may besynthesized from chiral starting materials or the racemates may beresolved by conventional procedures which are well known in the art ofchemistry such as chiral chromatography, fractional crystallization ofdiastereomeric salts and the like.

The compounds of Formula I are useful both in the free base form and inthe form of acid-addition salts, and, both forms are within the purviewof the invention. The acid-addition salts are often a more convenientform for use; and in practice, use of the salt form inherently amountsto use of the base form. The acids which can be used to prepare theacid-addition salts include preferably those which produce, whencombined with the free base, pharmaceutically-acceptable salts, that is,salts whose anions are relatively innocuous to the animal organism inpharmaceutical doses of the salts, so that the beneficial propertiesinherent in the free base are not vitiated by side effects ascribable tothe anions. In practicing the present invention it is convenient to usethe free base form or the hydrochloride, fumarate, toluenesulfonate,methanesulfonate or maleate salts. However, other appropriatepharmaceutically acceptable salts within the scope of the invention arethose derived from other mineral acids and organic acids. Theacid-addition salts of the basic compounds are prepared by standardprocedures well known in the art which include, but are not limitedthereto, dissolving the free base in an aqueous alcohol solutioncontaining the appropriate acid and isolating the salt by evaporatingthe solution, or by reacting the free base and an acid in an organicsolvent, in which case the salt separates directly, or is precipitatedwith a second organic solvent, or can be obtained by concentration ofthe solution. Although medicinally acceptable salts of the basiccompounds are preferred, all acid-addition salts are within the scope ofthe present invention. All acid-addition salts are useful as sources ofthe free base form even if the particular salt per se is desired only asan intermediate product, as, for example, when the salt is formed forpurposes of purification or identification, or when it is used as anintermediate in preparing a medicinally acceptable salt by, for example,ion exchange procedures.

The suitably substituted 2-halomethyl-1,2,5-thiadiazolidin-3-one1,1-dioxides of the formula II, which are required for the synthesis ofthe compounds of the formula I, can be prepared as shown in scheme B:##STR12## A suitably substituted 1,2,5-thiadiazolidin-3-one 1,1-dioxideof the formula IV, or an ammonium salt thereof, or a cesium salt thereof(prepared by the treatment of a compound of the formula IV in alower-alkanol solvent, i.e. methanol, with cesium carbonate at atemperature of about room temperature), in a suitable organic solvent,such as toluene, or dimethylformamide, is treated with an excess of ahalomethyl phenyl sulfide, wherein X is a halogen, preferably chlorine,in the presence of a catalytic amount of a tetralower-alkylammoniumhalide, such as tetrabutylammonium bromide, (note, however, that the useof the tetralower-alkylammonium halide is optional when the cesium saltof the compound of the formula IV is utilized), at a temperature in therange of about room temperature up to the boiling point of the solventused, preferably at the boiling point of the solvent used, to afford thecompounds of the formula VI. The compound of the formula VI can then betreated with an excess of a sulfuryl halide of the formula SO₂ X₂,wherein X is a halogen, preferably chlorine, in a suitable organicsolvent, such as methylene chloride, at a temperature of about roomtemperature, to afford the compounds of the formula II.

The suitably substituted 1,2,5-thiadiazolidin-3-one 1,1-dioxides of theformula IV can be prepared as shown in Scheme C: ##STR13## A suitablysubstituted compound of the formula VII wherein R is lower-alkyl, in anappropriate lower-alkanol solvent, such as methanol, is treated with anexcess of an alkali metal lower-alkoxide; i.e. sodium methoxide, at atemperature in the range of about room temperature up to the boilingpoint of the solvent used, followed by treatment with a proton source,such as BIO-RAD® 50W-X8 H⁺ ion exchange resin, to afford the compoundsof the formula IV.

Alternatively, when the compounds of the formula IV wherein R³ islower-alkyl are desired, one can proceed as illustrated in Scheme D:##STR14## A compound of the formula IV wherein R³ is hydrogen, istreated with an excess of a benzyl halide of the formula VIII, wherein Xis a halogen, preferably bromine, in a suitable organic solvent, i.e.toluene, dimethylformamide, or a mixture thereof, in the presence of acatalytic amount of a tetralower-alkylammonium halide, preferablytetrabutylammonium bromide, at a temperature in the range of about roomtemperature up to the boiling point of the solvent, or solvent mixtureused, to afford the compounds of the formula IX. The compounds of theformula IX can then be treated with an excess of an alkylating agent (R³X') of the formula X, wherein R³ is lower-alkyl and X' is a halogen,preferably iodine, in a suitable organic solvent, such astetrahydrofuran, in the presence of an excess of a base, such aspotassium tert-butoxide, at a temperature in the range of about 0° C. upto the boiling point of the solvent used, preferably at a temperature inthe range of about 0° C. up to about room temperature, to afford acompound of the formula XI. The compound of the formula XI can then bedebenzylated by treatment with an excess of an appropriate hydrogendonor, preferably ammonium formate, in the presence of an appropriatecatalyst, preferably palladium on carbon, in a suitable lower-alkanolsolvent, such as methanol, at a temperature in the range of about roomtemperature up to the boiling point of the solvent used, preferably at atemperature of about room temperature, to afford the compounds of theformula IV wherein R³ is lower-alkyl.

The compounds of the formula VII, which are required for the synthesisof the compounds of the formula IV, can be prepared as illustrated inScheme E: ##STR15## A halosulfonyl isocyanate of the formula XII,wherein X is a halogen, preferably chlorine, is treated with an excessof an α-amino acid ester of the formula XIII, wherein R is lower-alkyland X⁻ is a halogen, preferably chlorine, and an excess of benzylalcohol, in the presence of an excess of a base, such as triethylamine,in an appropriate organic solvent, such as methylene chloride, at atemperature in the range of about -10° C. up to about room temperature,to afford a compound of the formula XIV (Note, if desired, the α-aminoacid ester can be used as the limiting reagent rather than thehalosulfonyl isocyanate). The compound of the formula XIV can then behydrogenated at a hydrogen pressure of about 50-55 psi, in alower-alkanol solvent, such as methanol, in the presence of a catalyst,preferably palladium on carbon, to produce the compounds of the formulaVII.

The acids of the formula III are either commercially available or theycan be prepared by procedures known in the art (see, for example, U.S.Pat. Nos. 5,296,496 and 5,187,173 which are incorporated herein byreference). The halomethyl phenyl sulfides of the formula V, the benzylhalide of the formula VIII, the alkylating agent of the formula X, thehalosulfonyl isocyanate of the formula XII and the α-amino acid ester ofthe formula XIII are either commercially available, or they can beprepared by procedures known in the art, or by the procedures describedhereinbelow in the examples.

The structure of the compound of the invention were established by themode of synthesis, and by one or more of elemental analysis, andinfrared, nuclear magnetic resonance and mass spectroscopy. The courseof the reactions and the identity and homogeneity of the products wereassessed by one or more of thin layer chromatography (TLC), highpressure liquid chromatography (HPLC), or gas-liquid chromatography(GLC).

The following examples will further illustrate the invention without,however, limiting it thereto. All melting points (m.p.) are given indegrees centigrade (°C.) and are uncorrected.

EXAMPLE 1 (a)

To a stirred solution of 7.36 ml (84.8 mmol) of chlorosulfonylisocyanate in 150 ml of methylene chloride was added phenylmethanol(8.82 ml, 84.7 mmol) at 0°-5° C. After stirring the above solution for1.5 hours at this temperture, a solution of 15.62 g (93.25 mmol) of2-amino-pentanoic acid methyl ester hydrochloride in 500 ml of methylenechloride containing triethylamine (25.54 g, 0.2528 mol) was added at0°-5° C., and the resulting mixture was stirred overnight allowing themixture to warm to room temperature. The reaction mixture was pouredinto 600 ml of 10% aq. HCl solution, saturated with sodium chloride, andthe organic layer was separated. The aqueous layer was extracted withmethylene chloride/ethyl acetate (4:1, 2×200 ml) and the combinedorganic layer was washed with brine, dried and concentrated in vacuo toyield 2-(N-carbobenzyloxyaminosulfonyl)aminopentanoic acid methyl ester(Formula XIV: R═CH₃ ; R¹ ═H; R² ═propyl; R³ ═H) as a solid.

(b)

A solution of 2-(N-carbobenzyloxyaminosulfonyl)aminopentanoic acidmethyl ester (33 g) in methanol (250 ml) under nitrogen was cooled to 0°C. and 1.4 g of 10% Pd/C was added. The mixture was placed into a ParrApparatus and hydrogenated at 55 psi for 2 hours. The catalyst wasremoved on a pad of CELITE® and the filtrate was concentrated in vacuoand purified by flash silica gel chromatography (50% ethyl acetate inhexane) to afford 13.5 g (76%) of 2-(amino sulfonyl)aminopentanoic acidmethyl ester (Formula VII: R═CH₃ ; R¹ ═H; R² ═propyl; R³ ═H) as a solid.

(c)

A solution of 2-(aminosulfonyl)aminopentanoic acid methyl ester (13 g;0.05 mmol) in methanol (150 ml) was added to a solution of sodiummethoxide (5.54 g, from 2 g of Na) in 150 ml of methanol and theresulting reaction mixture was refluxed for 18 hours. The mixture wascooled, neutralized with BIO-RAD® 50W-X8 H⁺ ion exchange resin, andfiltered. The filtrate was concentrated in vacuo to yield an oil whichwas crystallized from methanol/hexane to afford 10.8 g (quantitative) of4-propyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide (Formula IV: R¹ ═H; R²═propyl; R³ ═H).

(d)

To a mixture of 4-propyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide (5.0 g,28.25 mmol) suspended in 150 ml of toluene was added phenylmethylbromide (5.32 g, 31.03 mmol) and tetrabutylammonium bromide (0.9 g, 0.28mmol). The resulting mixture was refluxed for 19 hours, cooled,filtered, and the filtrate was concentrated in vacuo. The residue waspurified by flash chromatography to afford 2.97 g (39%) of2-phenylmethyl-4-propyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide (FormulaIX: R¹ ═H; R² ═propyl) as a solid, m.p., 63.5°-65.5° C.

(e)

Potassium t-butoxide (1.05 g (9.37 mmol) was added to a solution of2-phenylmethyl-4-propyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide (2.4 g,8.95 mmol) in 25 ml of THF at 0° C. and the mixture was stirred at thistemperature for 1 hour. To the mixture was added methyl iodide (6.35 g,44.73 mmol) and the resulting mixture was allowed to stir at 0° C. for0.5 hour and at room temperature for 4 hours. The resulting mixture wasquenched with saturated ammonium chloride solution, extracted with ethylacetate and the organic layer was washed with brine. The organic layerwas dried, concentrated in vacuo, and the residue was purified by flashchromatography to afford 2.4 g (95%) of2-phenylmethyl-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide(Formula XI: R¹ ═H; R² ═propyl; R³ ═CH₃) as an oil.

(f)

To a suspension of 3.5 g of 10% Pd/C in 150 ml of methanol containingammonium formate (14 g) was added a solution of2-phenylmethyl-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide(8.7 g) in 40 ml of methanol. The mixture was stirred at roomtemperature for 15 hours, filtered through a pad of CELITE® and theresidue was washed with methanol. The combined filtrate was concentratedin vacuo to afford 7.6 g of 4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula IV: R¹ ═H; R² ═propyl; R³ ═CH₃) as a solid.

(g)

A mixture of 4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide (9g), phenylthiomethyl chloride (7.43 g) and tetrabutylammonium bromide (1g) suspended in 200 ml of toluene was refluxed for 8 hours, cooled, andconcentrated in vacuo. The residue was purified by flash chromatography(15-20% ethyl acetate in hexane) to afford 8.5 g (88%) of2-phenylthiomethyl-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula VI: R¹ ═H; R² ═propyl; R³ ═CH₃).

(h)

To a solution of2-phenylthiomethyl-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (8.4 g) in 150 ml of methylene chloride was added sulfurylchloride (3.22 ml) and the mixture was stirred for 3 hours at roomtemperature. The mixture was concentrated in vacuo and the residue waspurified by flash chromatography (silica gel) to afford 5.7 g of2-chloromethyl-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide(Formula II: R¹ ═H; R² ═propyl; R³ ═CH₃ ; X═Cl) as a solid.

(i)

A mixture of 2-chloromethyl-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (1 g; 4.16 mmol), diethyl phosphate (Formula III: A═B═Et)(0.96 g, 6.63 mmol), tetrabutylammonium bromide (94 mg, 0.29 mmol) andtriethylamine (0.63 g, 6.23 mmol) in methylene chloride (20 ml) wasallowed to reflux for 24 hours. After adding an additionaltetrabutylammonium bromide, the mixture was refluxed for an additional48 hours, and then cooled. The mixture was purified by silica gel flashchromatography (ethyl acetate/hexane) to afford 0.98 g (66%) of2-(diethoxyphosphinyloxymethyl)-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula I: A═B═Et; R¹ ═H; R² ═propyl; R³ ═CH₃) as an oil.

EXAMPLE 2 (a)

To a stirred solution of 7.36 ml (84.9 mmol) of chloro-sulfonylisocyanate in 150 ml of methylene chloride was added benzyl alcohol(8.82 ml, 84.7 mmol) at 0° C. over a period of 35 minutes. Afterstirring the above solution for 2 hours at this temperature, a solutionof 15.62 g (93.25 mmol) of DL-valine methyl ester hydrochloride inmethylene chloride containing triethylamine (36.36 ml) was added at0°-5° C., and the resulting mixture was stirred overnight allowing themixture to warm to room temperature. The reaction mixture was pouredinto 600 ml of a 10% aq. HCl solution, saturated with sodium chloride,and the organic layer was separated. The aqueous layer was extractedwith methylene chloride (2×200 ml) and the combined organic layer waswashed with brine, dried and concentrated in vacuo to yield 30 g ofN-(carbobenzyloxyaminosulfonyl)-DL-valine methyl ester (Formula XIV:R═CH₃ ; R¹ ═H; R² ═isopropyl; R³ ═H) as a solid.

(b)

A solution of N-(carbobenzyloxyaminosulfonyl)-DL-valine methyl ester(28.5 g) in methanol (200 ml) under nitrogen was cooled to 0° C. and 1.8g of 10% Pd/C was added. The mixture was placed into a Parr Apparatusand hydrogenated at 55 psi for 2 hours. The catalyst was removed on apad of CELITE® and the filtrate was concentrated in vacuo and purifiedby flash silica gel chromatography (ethyl acetate/hexane, 1:1) to afford17.2 g (46%) of N-(aminosulfonyl)-DL-valine methyl ester (Formula VII:R═CH₃ ; R¹ ═H; R² ═isopropyl; R³ ═H) as a solid.

(c)

A solution of freshly prepared sodium methoxide (6.41 g, from 2.3 g ofNa) in 100 ml of methanol was added a solution ofN-(aminosulfonyl)-DL-valine methyl ester (16.6 g; 0.079 mmol) inmethanol (150 ml) and the resulting reaction mixture was stirred for 6hours. The mixture was cooled, neutralized with BIO-RAD® 50W-X8 H⁺ ionexchange resin, and filtered. The filtrate was concentrated in vacuo toafford 16.4 g of a crude 4-isopropyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula IV: R¹ ═H; R² ═isopropyl; R³ ═H).

(d)

Eight grams (44.94 mmol) of 4-isopropyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (which was dissolved in methanol, brought to pH 5 with ionexchange resin, filtered, and concentrated in vacuo to remove methanol),phenylmethyl bromide (8.09 g, 47.2 mmol), and tetrabutylammonium bromide(1.5 g, 4.66 mmol) suspended in toluene/DMF (200 ml/50 ml) was allowedto react at 130° C. for 30 hours. The resulting mixture was cooled, theexcess toluene was concentrated in vacuo, and the residue was dilutedwith 200 ml of water and extracted with ether/ethyl acetate (4:1, 700ml). The organic layer was washed with water and brine, dried andconcentrated in vacuo to yield a residue which was purified by flashchromatography to afford 8.6 g (72%) of2-phenylmethyl-4-isopropyl-1,2,5-thiadiazol-idin-3-one 1,1-dioxide(Formula IX: R¹ ═H; R² ═isopropyl) as a solid.

(e)

To a solution of potassium t-butoxide (3.53 g, 29 mmol) in THF was addeda solution of 2-phenylmethyl-4-isopropyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (7.7 g, 29 mmol) in THF at 0° C. and the mixture was stirredat this temperature for 1 hour. To the mixture was added methyl iodide(20.38 g, 0.143 mol) and the resulting mixture was allowed to stir atroom temperature for 2.5 hours. The resulting mixture was quenched withbrine, extracted with ether, and the organic layer was washed withbrine. The organic layer was dried, concentrated in vacuo, and theresidue was purified by flash chromatography to afford 7.1 g (88%) of2-phenylmethyl-4-isopropyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula XI: R¹ ═H; R² ═isopropyl; R³ ═CH₃) as a solid.

(f)

To a suspension of 3.5 g of 10% Pd/C in 150 ml of methanol containingammonium formate (15 g) was added a solution of2-phenylmethyl-4-isopropyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (7.1 g) in 50 ml of methanol under nitrogen. The mixture wasstirred at room temperature for 7 hours, filtered through a pad ofCELITE® and the residue was washed with methanol. The combined filtratewas concentrated in vacuo to afford 15 g of4-isopropyl-5-methyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide 2-ammoniumsalt (Formula IV: R¹ ═H; R² ═isopropyl; R³ ═CH₃ as NH₄ ⁺ salt).

(g)

A mixture of 4-isopropyl-5-methyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide2-ammonium salt (5.26 g, 25.2 mmol), phenylthiomethyl chloride (5.6 g,35.2 mmol) and tetrabutylammonium bromide (0.81 g, 2.51 mmol) suspendedin 200 ml of toluene/DMF (3:1) was refluxed for 16 hours, cooled, andconcentrated in vacuo. The residue was diluted with 150 ml of water,extracted with ether/ethyl acetate (5:1, 600 ml), and the organic layerwas washed with water, brine, and dried. The organic solution wasconcentrated in vacuo and the residue was purified by flashchromatography to afford 6.47 g (82%) of2-phenylthiomethyl-4-isopropyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula VI: R¹ ═H; R² ═isopropyl; R³ ═CH₃) as a solid, m.p.82°-83° C.

(h)

To a solution of2-phenylthiomethyl-4-isopropyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (6.38 g, 23.31 mmol) in 150 ml of methylene chloride wasadded sulfuryl chloride (2.5 ml, 30.4 mmol) and the mixture was stirredfor 2 hours at room temperature. The mixture was concentrated in vacuoand the residue triturated in hexane to afford 4.32 g (88%) of2-chloromethyl-4-isopropyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula II: R¹ ═H; R² ═isopropyl; R³ ═CH₃ ; X═Cl) as asolid, m.p. 118.5°-119.5° C.

(i)

2-Chloromethyl-4-isopropyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (0.5 g) was added to a solution of diethyl phosphate(Formula III: A═B═Et) (0.48 g) in methylene chloride containingtriethylamine (0.31 g), and the mixture was allowed to reflux for 48hours and then cooled. The mixture was concentrated in vacuo and theresidue purified by silica gel flash chromatography (ethylacetate/hexane) to afford 0.36 g (48%) of2-(diethoxyphosphinyloxymethyl)-4-isopropyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula I: R¹ ═H; R² ═isopropyl; R³ ═CH₃ ; A═B═Et) as anoil.

EXAMPLE 3 (a)

To a stirred solution of 7.36 ml (84.9 mmol) of chloro-sulfonylisocyanate in 150 ml of methylene chloride was added benzyl alcohol(8.82 ml, 84.7 mmol) at 0°-5° C. After stirring the above solution for1.5 hours at this temperature, a solution of 15.62 g (93.25 mmol) of2-amino-pentanoic acid methyl ester hydrochloride in 500 ml of methylenechloride containing triethylamine (25.54 g, 0.2528 mol) was added at0°-5° C., and the resulting mixture was stirred overnight allowing themixture to warm to room temperature. The reaction mixture was pouredinto 600 ml of a 10% aq. HCl solution, saturated with sodium chloride,and the organic layer was separated. The aqueous layer was extractedwith methylene chloride/ethyl acetate (4:1, 2×200 ml) and the combinedorganic layer was washed with brine, dried and concentrated in vacuo toyield 28.2 g (87.6%) of 2-(N-carbobenzyloxyaminosulfonyl)aminopentanoicacid methyl ester (Formula XIV: R═CH₃ ; R¹ ═H; R² ═propyl; R³ ═H) as asolid.

(b)

A solution of 2-(N-carbobenzyloxyaminosulfonyl)aminopentanoic acidmethyl ester (26.7 g) in methanol (200 ml) under nitrogen was cooled to0° C. and 1.5 g of 5% Pd/C was added. The mixture was placed into a ParrApparatus and hydrogenated for 2 hours. The catalyst was removed on apad of CELITE® and the filtrate was concentrated in vacuo and purifiedby flash silica gel chromatography (4-6% methanol in methylene chloride)to afford 11.0 g (62%) of 2-(aminosulfonyl)aminopentanoic acid methylester (Formula VII: R═CH₃ ; R¹ ═H; R² ═propyl; R³ ═H) as a solid, m.p.63°-64° C.

(c)

A solution of 2-(aminosulfonyl)aminopentanoic acid methyl ester (10.5 g;0.05 mmol) in methanol (100 ml) was added to a solution of sodiummethoxide (3.78 g, from 1.61 g of Na) in 100 ml of methanol and theresulting reaction mixture was refluxed for 18 hours. The mixture wascooled, neutralized with BIO-RAD® 50W-X8 H⁺ ion exchange resin, andfiltered. The filtrate was concentrated in vacuo to yield an oil whichwas crystallized from methanol/hexane to afford 6.5 g (73%) of4-propyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide (Formula IV: R¹ ═H; R²═propyl; R³ ═H).

(d)

To a mixture of 4-propyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide (5.1 g,28.65 mmol) suspended in 210 ml of toluene was added tetrabutylammoniumbromide (0.92 g, 2.86 mmol) and phenylthiomethyl chloride (4.93 g, 2.86mmol) and the resulting mixture was refluxed for 18 hours. The mixturewas cooled, filtered, and the filtrate was concentrated in vacuo. Theresidue was purified by silica gel flash column chromatography (20%ethyl acetate in hexane) to afford 5.39 g (63%) of2-phenylthiomethyl-4-propyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide(Formula VI: R¹ ═H; R² ═propyl; R³ ═H).

(e)

To a solution of 2-phenylthiomethyl-4-propyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (5.23 g, 17.43 mmol) in 200 ml of methylene chloride wasadded sulfuryl chloride (2.15 ml, 26.07 mmol) and the mixture wasstirred for 3 hours at room temperature. The mixture was concentrated invacuo, the residue triturated in hexane (200ml) for 2 hours, and theresulting solid was filtered and dried to afford 3.54 g (90%) of2-chloromethyl-4-propyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide (FormulaII: R¹ ═H; R² ═propyl; R³ ═H; X═Cl) as a solid.

(f)

2-Chloromethyl-4-propyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide (1 g;4.42 mmol) was added to a solution of diethyl phosphate (Formula III:A═B═Et) (1.02 g; 6.62 mmol) in methylene chloride (5 ml) containingtriethylamine (0.67 g; 6.63 mmol), and the mixture was allowed to refluxfor 24 hours and then cooled. The mixture was concentrated in vacuo andthe residue purified by silica gel flash chromatography (50% ethylacetate/hexane) to afford 0.54 g (35%) of2-(diethoxyphosphinyloxymethyl)-4-propyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula I: R¹ ═H; R2═propyl; R³ ═H; A═B═Et) as an oil.

EXAMPLE 4 (a)

To a solution of N-t-butoxycarbonyl-sarcosine (50 g; 0.264 mol) in 700ml of benzene was added 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU; 40.19g, 0.264 mol) in one portion. To the above clear solution was added74.84 g (0. 528 mol) of methyl iodide in one portion and the resultingclear solution was allowed to reflux for 7 hours. After addingadditional methyl iodide (16 ml), the reaction mixture was refluxed withstirring and cooled to room temperature, and stirred overnight. Thereaction mixture was filtered, the residue washed with ether, and thecombined filtrate was washed with water, saturated sodium bicarbonatesolution, and brine. The resulting organic layer was dried over sodiumsulfate, filtered, and concentrated in vacuo to afford 46.38 g (86.4 %)of N-t-butoxycarbonyl-sarcosine methyl ester as a yellow oil.

(b)

A 2M solution of LDA (70.32 ml, 0.14 mol) was added (via syringe) to asolution of N-t-butoxycarbonyl-sarcosine methyl ester (26 g, 0.1279 mol)in 40 ml of dry THF at -78° C. under nitrogen and the mixture wasstirred at this temperature for 30 minutes. To the above mixture wasadded 4-bromo-2-methyl-2-butene (20 g, 0.134 mol) with stirringcontinuing at -78° C., and the resulting mixture was allowed to warm toroom temperature. The reaction mixture was quenched with 6 ml ofsaturated ammonium chloride solution at -78° C., 20 ml of water wasadded, and the resulting reaction mixture was extracted with ethylacetate. The organic layer was washed with water and brine, dried oversodium sulfate, and concentrated in vacuo to yield a yellow oil, whichwas purified by silica gel column chromatography (20% ethyl acetate inhexane) to afford 22.1 g (63.7%) ofN-t-butoxyccarbonyl-2-(3-methyl-2-butenyl)-sarcosine methyl ester as anoil.

(c)

A solution of N-t-butoxycarbonyl-2-(3-methyl-2-butenyl)-sarcosine methylester (22.1 g, 81.44 mmol) in 400 ml of methanol under nitrogen wascooled to 0° C. and 1.5 g of 10% Pd/C was added. The mixture was placedinto a Parr Apparatus and hydrogenated at 50 psi for 6 hours. Thecatalyst was removed on a pad of CELITE® and the filtrate wasconcentrated in vacuo to afford 22.04 g (99%) ofN-t-butoxycarbonyl-2-(3-methylbutyl)-sarcosine methyl ester as an oil.

(d)

A mixture of N-t-butoxycarbonyl-2-(3-methylbutyl)-sarcosine methyl ester(22.04 g, 80.62 mmol) in 360 ml of ethereal HCl was stirred at roomtemperature for 3 days. The resulting mixture was cooled in an ice/bathand the solvent was concentrated in vacuo to afford, after drying, 13.17g (78%) of 2-(3-methylbutyl)-sarcosine methyl ester hydrochloride(Formula XIII: R═CH₃ ; R¹ ═H; R² ═(CH₂)₂ CH(CH₃)₂ ; R³ ═CH₃ ; X⁻ ═Cl⁻)which was recrystallized from methanol/ether, m.p. 110°-111° C.

(e)

To a stirred solution of 5.77 ml (66.78 mmol) of chloro-sulfonylisocyanate in methylene chloride was added under nitrogen benzyl alcohol(6.89 ml, 66.57 mmol) at 0°-5° C. After stirring the above solution for1 hour, a solution of 13.166 g (62.78 mmol) of2-(3-methylbutyl)-sarcosine methyl ester hydrochloride in methylenechloride containing triethylamine (27.33 ml, 194.62 mmol) was added at0°-5° C., and the resulting mixture was stirred overnight allowing themixture to warm to room temperature. The reaction mixture was pouredinto 600 ml of a 10% aq. HCl solution, saturated with sodium chloride,and the organic layer was separated. The aqueous layer was extractedwith methylene chloride and the combined organic layer was washed withbrine, dried over magnesium sulfate and concentrated in vacuo to yield21.22 g (87.2%) ofN-(carbobenzyloxyaminosulfonyl)-2-(3-methylbutyl)-sarcosine methyl ester(Formula XIV: R═CH₃ ; R¹ ═H; R² ═(CH₂)₂ CH(CH₃)₂ ; R³ ═CH₃) which waspurified by silica column chromatography (20% ethyl acetate in hexane)as an oil.

(f)

A solution ofN-(carbobenzyloxyaminosulfonyl)-2-(3-methylbutyl)-sarcosine methyl ester(20.6 g, 53.17 mmol) in 200 ml of methanol under nitrogen was cooled to0° C. and 1.5 g of 10% Pd/C was added. The mixture was placed into aParr Apparatus and hydrogenated for 3.5 hours. The catalyst was removedon a pad of CELITE® and the filtrate was concentrated in vacuo to afford13.24 g (98.6%) of N-(aminosulfonyl)-2-(3-methylbutyl)-sarcosine methylester (Formula VII: R═CH₃ ; R¹ ═H; R² ═(CH₂)₂ CH(CH₃)₂ ; R³ ═CH₃) as anoil.

(g)

A solution of N-(aminosulfonyl)-2-(3-methylbutyl)-sarcosine methyl ester(12.28 g, 48.67 mmol) in methanol (150 ml) was added under nitrogen to asolution of sodium methoxide (Na=2.1 g, 95.71 mmol)) in 150 ml ofice-cold methanol. The resulting reaction mixture was stirred at roomtemperature under nitrogen for 1.5 hours, and then the mixture wastreated with 25 g of ion-exchange resin (BIO RAD® Ag 50W-x8; 200-400mesh) for 40 minutes and filtered. The filtrate was concentrated invacuo to afford 10.7 g (99.8%) of4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide sodiumsalt (Formula IV: R¹ ═H; R² ═(CH₂)₂ CH(CH₃)₂ ; R³ ═H; as the sodiumsalt) as a solid, m.p. 212°-214° C.

(h)

A mixture of 4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide cesium salt (prepared by reacting 7.7 g (34.95 mmol) of thecompound of example 4(g) in methanol with 5.13 g of CS₂ CO₃, followed byremoval of the solvent and drying under high vacuum) andphenylthiomethyl chloride (6.65 g, 41.94 mmol) suspended in DMF washeated at 85° C. for 17 hours. The mixture was cooled, and poured into300 ml of ice/water. The reaction mixture was extracted with ethylacetate (3×) and the organic layer was washed with water and brine, anddried over sodium sulfate. The organic layer was concentrated in vacuoand the residue was purified by silica column chromatography (10% ethylacetate in hexane) to afford 8.15 g (70.6%) of2-phenylthiomethyl-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula VI: R¹ ═H; R² ═(CH₂)₂ CH(CH₃)₂ ; R³ ═CH₃) as asolid.

(i)

To a solution of2-phenylthiomethyl-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (8.15 g, 24.66 mmol) in 200 ml of methylene chloride wasadded in one portion sulfuryl chloride (2.36 ml, 2 9.6 mmol) and themixture was stirred for 3.5 hours at room temperature. The mixture wasconcentrated in vacuo and the residue was triturated in hexane to afford4.64 g (70%) of2-chloromethyl-4-(3-methylbutyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula II: R¹ ═H; R² ═(CH₂)₂ CH(CH₃)₂ ; R³ ═CH₃ ; X═Cl) asa solid, m.p. 59°-60° C.

(j)

To the cesium salt of dibenzyl phosphate (Formula III: A═B═CH₂ Ph)(prepared from 2.07 g of the phosphate and 1.21 g of cesium carbonate inmethanol followed by removal of the methanol) in 30 ml of DMF was added2-chloromethyl-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (1 g; 3.72 mmol) and the mixture was allowed to stir at roomtemperature for 48 hours. The mixture was poured into ice/water,extracted with ethyl acetate, and the organic layer was washed withwater, brine and dried. The solvent was concentrated in vacuo and theresidue purified by silica gel flash chromatography (60% ethylacetate/hexane) to afford 0.29 g (15%) of2-(dibenzyloxyphosphinyloxymethyl)-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula I: R¹ ═H; R² ═(CH₂)₂ CH(CH₃)₂ ; R³ ═CH₃ ; A═B═CH₂Ph) as an oil.

EXAMPLE 5 (a)

Following a procedure similar to that described in example 4(b), butsubstituting 2.1 equivalents of methyl iodide for4-bromo-2-methyl-2-butene and utilizing 2.2 equivalents of lithiumdiisopropyl amide (LDA) it is contemplated that there can be prepared acompound of the formula: (CH₃)₂ C(CO₂ CH₃)N(CH₃)(CO₂ tBu).

(b)

Following a procedure similar to that described in example 4(d), butsubstituting the compound example 5(a) for the compound of example 4(c),it is contemplated that there can be prepared a compound of the formula(CH₃)₂ C(CO₂ CH₃)NH(CH₃).HCl.

Following procedures similar to those described in Examples 1(a)-(c) butsubstituting an appropriate α-amino acid ester of the formula XIII fornorvaline methyl ester hydrochloride in example 1(a), it is contemplatedthat there can be prepared the following compounds of the formula IVillustrated in Table I.

                  TABLE I                                                         ______________________________________                                         ##STR16##                     IV                                             Example                                                                       No.    R.sup.1 R.sup.2                                                                              R.sup.3                                                                            Ester Used                                         ______________________________________                                        6      CH.sub.3                                                                              CH.sub.3                                                                             CH.sub.3                                                                           (CH.sub.3).sub.2 C(NHCH.sub.3)CO.sub.2                                        CH.sub.3.HCl                                       7      CH.sub.2 Ph                                                                           H      H    C.sub.6 H.sub.5 CH.sub.2 CH(NH.sub.2)CO.sub.2                                 CH.sub.3.HCl                                       ______________________________________                                    

Following a procedure similar to that described in Example 1(g) butsubstituting an appropriate compound of the Formula IV for4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide it iscontemplated that there can be prepared the following compounds of theformula VI illustrated in Table II:

                  TABLE II                                                        ______________________________________                                         ##STR17##                     VI                                             Example No.    R.sup.1    R.sup.2  R.sup.3                                    ______________________________________                                        8              CH.sub.3   CH.sub.3 CH.sub.3                                   9              CH.sub.2 Ph                                                                              H        H                                          ______________________________________                                    

Following a procedure similar to that described in example 1(h), butsubstituting an appropriate compound of the formula VI for2-phenylthiomethyl-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide it is contemplated that there can be prepared the followingcompounds of the formula II illustrated in Table III:

                  TABLE III                                                       ______________________________________                                         ##STR18##                     II                                             Example No.  R.sup.1   R.sup.2  R.sup.3                                                                              X                                      ______________________________________                                        10           CH.sub.3  CH.sub.3 CH.sub.3                                                                             Cl                                     11           CH.sub.2 Ph                                                                             H        H      Cl                                     ______________________________________                                    

Following a procedure similar to that described in example 1(i), butsubstituting an appropriate acid of the formula III for ##STR19## and,if applicable, an appropriate compound of the formula II for2-chloromethyl-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide,it is contemplated that the following compounds of the formula Iillustrated in table IV can be prepared.

                  TABLE IV                                                        ______________________________________                                         ##STR20##                     I                                              Example No.                                                                            A         B        R.sup.1                                                                              R.sup.2                                                                             R.sup.3                              ______________________________________                                        12       CH.sub.2 CH.sub.3                                                                       CH.sub.2 CH.sub.3                                                                      CH.sub.3                                                                             CH.sub.3                                                                            CH.sub.3                             13       CH.sub.2 CH.sub.3                                                                       CH.sub.2 CH.sub.3                                                                      CH.sub.2 Ph                                                                          H     H                                    14       Ph        CH.sub.3 H      Propyl                                                                              CH.sub.3                             15       CH.sub.3  CH.sub.2 CH.sub.3                                                                      H      Propyl                                                                              CH.sub.3                             ______________________________________                                    

EXAMPLE 16

It is contemplated that2-(dihydroxyphosphinyloxymethyl)-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (Formula I: R² ═(CH₂)CH(CH₃)₂ ; R¹ ═H; R³ ═CH₃ ; A═B═H), canbe prepared by the hydrogenation of2-(dibenzyloxyphosphinyloxymethyl)-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide in methanol in the presence of 10% palladium on carbon.

EXAMPLE 17 (a)

To a stirred solution of 7.36 ml (85 mmol) of chlorosulfonyl isocyanatein 180 ml of methylene chloride was added phenylmethanol (8.82 ml, 85mmol) at 0° C. over a period of 35 minutes. After stirring the abovesolution for 2 hours at this temperature, a solution of 16.65 g (93mmol) of 2-piperidinecarboxylic acid methyl ester hydrochloride inmethylene chloride (500 mL) containing triethylamine (35.3 ml) was addedat 0°-5° C., and the resulting mixture was stirred overnight allowingthe mixture to warm to room temperature. The reaction mixture was pouredinto 600 ml of 10% aq. HCl solution, saturated with sodium chloride, andthe organic layer was separated. The aqueous layer was extracted withmethylene chloride (2×200 ml) and the combined organic layer was washedwith brine, dried and concentrated in vacuo to yield 31 g ofN-(carbobenzyloxyaminosulfonyl)-2-piperidinecarboxylic acid methyl ester(Formula XIV: R¹ ═H; R² and R³ together═--(CH₂)₄ --; R═CH₃) as a solid.

(b)

A solution of N-(carbobenzyloxyaminosulfonyl)-2-piperidinecarboxylicacid methyl ester (29.8 g) in methanol (300 ml) under nitrogen wascooled to 0° C. and 1.8 g of 10% Pd/C was added. The mixture was placedinto a Parr Apparatus and hydrogenated for 2 hours at 55 psi. Thecatalyst was removed on a pad of CELITE® and the filtrate wasconcentrated in vacuo and purified by flash silica gel chromatography(35-40% ethyl acetate/hexane) to afford 17 g (46%) ofN-(aminosulfonyl)-2-piperidinecarboxylic acid methyl ester (Formula VII:R═CH₃ ; R¹ ═H; R² and R³ together═--(CH₂)₄ --) as a solid, m.p. 72°-74°C.

(c)

To a solution of freshly prepared sodium methoxide (6.05 g, from 2.1 gof Na) in 150 ml of methanol was added a solution ofN-(aminosulfonyl)-2-piperidinecarboxylic acid methyl ester (15 g; 0.067mmol) in methanol (100 ml) and the resulting reaction mixture wasstirred at room temperature for 2 hours. The mixture was cooled,neutralized with BIO-RAD® 50W-X8 H⁺ ion exchange resin, and filtered.The filtrate was concentrated in vacuo to afford 14.4 g of1,2,5-thiadiazolo[2,3-a]3,3a, 4,5,6,7-hexahydropyridine-3-one1,1-dioxide (Formula IV: R¹ ═H; R² and R³ together═--(CH₂)₄ --).

(d)

To a mixture of1,2,5-thiadiazolo[2,3-a]3,3a,4,5,6,7-hexahydropyridine-3-one 1,1-dioxide(10.0 g, 52.6 mmol) suspended in 400 ml of toluene was addedphenylthiomethyl chloride (10.85 g, 68.4 mmol) and tetrabutylammoniumbromide (1.69 g). The resulting mixture was refluxed for 6 hours,cooled, filtered, and the filtrate was concentrated in vacuo. Theresidue was purified by flash column chromatography (25% ethyl acetatein hexane) to afford 12.83 g (78%) of2-phenylthiomethyl-1,2,5-thiadiazolo[2,3-a]3,3a,4,5,6,7-hexahydropyridine-3-one1,1-dioxide (Formula VI: R¹ ═H; R² and R³ together═--(CH₂)₄ --) as anoil.

(e)

To a solution of2-phenylthiomethyl-1,2,5-thiadiazolo[2,3-a]3,3a,4,5,6,7-hexahydropyridine-3-one1,1-dioxide (12 g) in 250 ml of methylene chloride was added sulfurylchloride (4.63 ml) and the mixture was stirred for 3 hours at roomtemperature. The mixture was concentrated in vacuo, the residuetriturated in hexane (200ml) for 2 hours, the resulting solid filteredand washed with hexane to afford, after drying, 8.1 g (88%) of2-chloromethyl-1,2,5-thiadiazolo[2,3-a]3,3a,4,5,6,7-hexahydropyridine-3-one1,1-dioxide (Formula II: R¹ ═H; R² and R³ together═--(CH₂)₄ --; X═Cl) asa solid, m.p. 124°-125.5° C.

(f)

2-Chloromethyl-1,2,5-thiadiazolo[2,3-a]-3,3a,4,5,6,7-hexahydropyridine-3-one1,1-dioxide (1 g; 4.42 mmol) was added to a solution of diethylphosphate (Formula III: A═B═Et) (1.02 g, 6.62 mmol) and triethylamine(0.67 g, 6.63 mmol) in methylene chloride (5 ml) at room temperature,and the mixture was allowed to reflux for 24 hours and then cooled. Themixture was purified by silica gel flash chromatography (ethylacetate/hexane) to afford 0.3 g (22%) of2-(diethoxyphosphinyloxymethyl)-1,2,5-thiadiazolo[2,3-a]3,3a,4,5,6,7-hexahydropyridine-3-one1,1-dioxide (Formula I: A═B═Et; R¹ ═H; R² and R³ together═--(CH₂)₄ --)as an oil.

Biological Test Results

Representative examples of the compounds of the invention have beenfound to possess valuable pharmacological properties. In particular,they have been found to inhibit the activity of serine proteases,specifically human leukocyte elastase, and are thus useful in thetreatment of degenerative disease conditions such as emphysema,rheumatoid arthritis, pancreatitis, cystic fibrosis, chronic bronchitis,adult respiratory distress syndrome, inflammatory bowel disease,psoriasis, bullous pemphigoid, periodontal disease, andalpha-1-antitrypsin deficiency.

The pharmacological properties of representative examples of thecompounds of the invention were demonstrated by the followingconventional in vitro biological test procedure.

The test compound (inhibitor) is dissolved in DMSO in a vial to producean inhibitor stock solution which has a concentration in the range of200-1000 μM. The inhibitor stock solution is diluted (1:4, 1:16 and1:64) into assay vials (vials 1, 2 and 3 respectively) containing 2.4 mLof buffer solution (50 mMN-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid]/NaOH, 500 mMNaCl, pH 7.8 at 25° C.) and DMSO is added so that the total volume ineach vial is 3.2 mL. 70 μL, 50 μL, 35 μL and 25 μL of inhibitor fromassay vial 1 is placed into the first four wells of a 96-well microtiterplate and each well is made up to 90 μL total volume with the additionof a 25% DMSO/buffer solution. The inhibitor from assay vials 2 and 3 isprocessed in a similar manner and placed in wells 5-12 respectively toafford a total of 12 different inhibitor concentrations. Four wells(wells 13-16) containing 90 μL of the 25% DMSO/buffer solution but noinhibitor are also run simultaneously with the inhibited wells as acontrol. 150 μL of substrate solution (prepared by the addition of 500μL of the human leukocyte elastase (HLE) substrateMeOSuc-Ala-Ala-Pro-Val-pNA (18.7 mM in DMSO) to 19.5 mL of buffersolution) is then added simultaneously into each of the 16 wells and thesolution in each well was thoroughly mixed.

The 96-well microtiter plate is placed into a Microplate Reader #89815Aspectrophotometer and 110 μL of the enzyme solution (prepared asfollows: a mixture of 20 mL of buffer solution and 20 mg of bovine serumalbumen is gently vortexed in a scintillation vial and 5 μL HLE stocksolution (1 mg/mL dissolved in deionized water) is added) is addedsimultaneously to each of the 16 wells. Each of the solutions in thewells is throughly mixed and then the time-dependent absorbance data iscollected at an absorbance of 410 nM until the assay is complete. Itshould be noted that although this assay method can be done manually, itis preferred to perform the assay robotically using a Hewlett PackardMicroAssay System Robot.

A plot of the absorbance versus time data thus obtained affords progresscurves the final slope of which is equal to the final steady-statevelocities (VF). Using the program ENZFITTER (Elsevier software), theprogress curves for the four control assays ([I]=0) are fit by linearregression to yield the enzyme reaction velocity values in the absencesof inhibitor (V_(o)) which are averaged to produce a single fixed value.The inhibition constant K_(i) (nM) is then obtained from a plot of##EQU1## which affords a linear plot wherein: ##EQU2## and [S] is theconcentration of the substrate and K_(m) is the Michaelis constant.

Table V summarizes the results obtained from the testing ofrepresentative compounds of the invention for human leukocyte elastaseinhibitory activity.

                  TABLE V                                                         ______________________________________                                        Example No.    K.sub.i (nM)                                                   ______________________________________                                        1(i)            2                                                             2(i)           680                                                            3(f)            25                                                            4(j)            1.5                                                           17(f)          500                                                            ______________________________________                                    

The compounds of the invention can be prepared for pharmaceutical use byconventional pharmaceutical procedures that are well known in the art;that is, by formulating a pharmaceutical composition which comprisescompounds of the invention or their pharmaceutically acceptable saltstogether with one or more physiologically acceptable carriers,adjuvants, diluents or vehicles, for oral administration in solid orliquid form, parenteral administration, topical administration oraerosol inhalation administration, and the like.

Solid compositions for oral administration include compressed tablets,pills, powders and granules. In such solid compositions, the activecompound is admixed with at least one inert diluent such as starch,calcium carbonate, sucrose or lactose. These compositions may alsocontain additional substances other than inert diluents, e.g.,lubricating agents, such as magnesium stearate, talc and the like.

Liquid compositions for oral administration include pharmaceuticallyacceptable emulsions, solutions, suspensions, syrups and elixirscontaining inert diluents commonly used in the art, such as water andliquid paraffin. Besides inert diluents such compositions may alsocontain adjuvants, such as wetting and suspending agents, andsweetening, flavoring, perfuming and preserving agents. According to theinvention, the compounds for oral administration also include capsulesof absorbable material, such as gelatin, containing said activecomponent with or without the addition of diluents or excipients.

Preparations according to the invention for parenteral administrationinclude sterile aqueous, aqueous-organic, and organic solutions,suspensions and emulsions. Examples of organic solvents or suspendingmedia are propylene glycol, polyethylene glycol, vegetable oils such asolive oil and injectable organic esters such as ethyl oleate. Thesecompositions can also contain adjuvants such as stabilizing, preserving,wetting, emulsifying and dispersing agents.

Preparations according to the invention for topical administration oraerosol inhalation administration include dissolving or suspending acompound of the invention in a pharmaceutically acceptable vehicle suchas water, aqueous alcohol, glycol, oil solution or oil-water emulsion,and the like.

If desired, the compounds of the invention can further be incorporatedinto slow release or targeted delivery systems such as polymer matrices,liposomes, and microspheres.

The percentage of active component in such compositions may be varied sothat a suitable dosage is obtained. The dosage administered to aparticular patient is variable depending upon the clinician's judgmentusing as criteria: The route of administration, the duration oftreatment, the size and physical condition of the patient, the potencyof the active component and the patient's response thereto. An effectivedosage amount of the active component can thus readily be determined bythe clinician after a consideration of all criteria and using his bestjudgment on the patient's behalf.

We claim:
 1. A compound of the formula: ##STR21## wherein R¹ ishydrogen, lower-alkyl, or phenyl-lower-alkyl; R² is hydrogen,lower-alkyl, or phenyl-lower-alkyl; R³ is hydrogen, or lower-alkyl; orR² and R³ together are --(CH₂)_(n) -- wherein n is 3 or 4; and A and Bare independently hydrogen, lower-alkyl, phenyl, or phenyl-lower-alkyl;or a pharmaceutically acceptable acid-addition salt thereof; or whereapplicable, an enantiomer or a racemic mixture thereof.
 2. A compoundaccording to claim 1 wherein A and B are independently hydrogen,lower-alkyl, or phenyl-lower-alkyl.
 3. A compound according to claim 2wherein R¹ is hydrogen, or lower-alkyl; R² is hydrogen, or lower-alkyl;and R³ is hydrogen or lower-alkyl; or R² and R³ together are --(CH₂)_(n)--.
 4. A compound according to claim 3 wherein A and B are independentlylower-alkyl or phenyl-lower-alkyl.
 5. A compound according to claim 4wherein A and B are independently ethyl, or phenylmethyl; R² is hydrogenor lower-alkyl; and R³ is hydrogen or methyl; or R² and R³ together are--(CH₂)₄ --.
 6. A compound according to claim 5 wherein R¹ is hydrogen,propyl, isopropyl, or 3-methylbutyl; R² is hydrogen, propyl, isopropyl,or 3-methylbutyl; and R³ is hydrogen or methyl; or R² and R³ togetherare --(CH₂)₄ --. 7.2-(Diethoxyphosphinyloxymethyl)-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide according to claim 6.8.2-(Dibenzyloxyphosphinyloxymethyl)-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide according to claim
 6. 9. A pharmaceutical composition forthe treatment of degenerative diseases which comprises apharmaceutically acceptable carrier, adjuvant, diluent or vehicletogether with an effective proteolytic enzyme inhibiting amount of acompound of the formula: ##STR22## wherein R¹ is hydrogen, lower-alkyl,or phenyl-lower-alkyl; R² is hydrogen, lower-alkyl, orphenyl-lower-alkyl; R³ is hydrogen, or lower-alkyl; or R² and R³together are --(CH₂)_(n) -- wherein n is 3 or 4; and A and B areindependently hydrogen, lower-alkyl, phenyl, or phenyl-lower-alkyl; or apharmaceutically acceptable acid-addition salt thereof; or whereapplicable, an enantiomer or a racemic mixture thereof.
 10. Apharmaceutical composition according to claim 9 wherein A and B areindependently hydrogen, lower-alkyl, or phenyl-lower-alkyl; R¹ ishydrogen, or lower-alkyl; R² is hydrogen, or lower-alkyl; and R³ ishydrogen or lower-alkyl; or R² and R³ together are --(CH₂)_(n) --.
 11. Apharmaceutical composition according to claim 10 wherein A and B areindependently lower-alkyl, or phenyl-lower-alkyl.
 12. A pharmaceuticalcomposition according to claim 11 wherein R¹ is hydrogen, propyl,isopropyl, or 3-methylbutyl; R² is hydrogen, propyl, isopropyl, or3-methylbutyl; R³ is hydrogen or methyl; or R² and R³ together are--(CH₂)₄ --; and A and B are independently ethyl or phenylmethyl.
 13. Apharmaceutical composition according to claim 12 wherein the compound is2-(diethoxyphosphinyloxymethyl)-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide.
 14. A pharmaceutical composition according to claim 12wherein the compound is2-(dibenzyloxyphosphinyloxymethyl)-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide.
 15. A method for the treatment of degenerative diseaseswhich comprises administering to a patient in need of such treatment aneffective proteolytic enzyme inhibiting amount of a compound of theformula: ##STR23## wherein R¹ is hydrogen, lower-alkyl, orphenyl-lower-alkyl; R² is hydrogen, lower-alkyl, or phenyl-lower-alkyl;R³ is hydrogen, or lower-alkyl; or R² and R³ together are --(CH₂)_(n) --wherein n is 3 or 4; and A and B are independently hydrogen,lower-alkyl, phenyl, or phenyl-lower-alkyl; or a pharmaceuticallyacceptable acid-addition salt thereof; or where applicable, anenantiomer or a racemic mixture thereof.
 16. A method according to claim15 wherein A and B are independently hydrogen, lower-alkyl, orphenyl-lower-alkyl; R¹ is hydrogen, or lower-alkyl; R² is hydrogen, orlower-alkyl; and R³ is hydrogen or lower-alkyl; or R² and R³ togetherare --(CH₂)_(n) --.
 17. A method according to claim 16 wherein A and Bare independently lower-alkyl, or phenyl-lower-alkyl.
 18. A methodaccording to claim 17 wherein R¹ is hydrogen, propyl, isopropyl, or3-methylbutyl; R² is hydrogen, propyl, isopropyl, or 3-methylbutyl; R³is hydrogen, or methyl; or R² and R³ together are --(CH₂)₄ --; and A andB are independently ethyl, or phenylmethyl.
 19. A method according toclaim 18 wherein the compound is2-(diethoxyphosphinyloxymethyl)-4-propyl-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide.
 20. A method according to claim 18 wherein the compound is2-(dibenzyloxyphosphinyloxymethyl)-4-(3-methylbutyl)-5-methyl-1,2,5-thiadiazolidin-3-one1,1-dioxide.
 21. A method according to claim 15 wherein saiddegenerative diseases are selected from emphysema, rheumatoid arthritis,pancreatitis, cystic fibrosis, chronic bronchitis, adult respiratorydistress syndrome, inflammatory bowel disease, psoriasis, bullouspemphigoid, periodontal disease, and alpha-1-antitrypsin deficiency. 22.A method according to claim 21 wherein said degenerative diseases areselected from emphysema, cystic fibrosis, chronic bronchitis, and adultrespiratory distress syndrome.